1. Field of the Invention
This disclosure is generally related to electrical power systems, and more specifically to power converter architectures such as power modules suitable for rectifying, inverting and/or converting electrical power between power sources and loads.
2. Description of the Related Art
Power converters are used to transform and/or condition power from one or more power sources to supply to one or more loads. An inverter is commonly used to transform direct current (DC) to alternating current (AC), for use in supplying power to an AC load. A rectifier is commonly used to transform AC to DC. A DC/DC converter is commonly used to step up or step down a DC voltage. An appropriately configured and operated power converter may perform any one or more of these functions. As used herein and in the claims which follow, the term “converter” applies to all converters whether inverters, rectifiers and/or DC/DC converters.
A large variety of applications require power transformation and/or conditioning. For example, a DC power source such as a fuel cell system, battery and/or ultracapacitor may produce DC power, which must be inverted to supply power to an AC load such as a three phase AC motor in an electric or hybrid vehicle. A photovoltaic array may produce DC power that must be inverted to supply or export AC power to a power grid of a utility. An AC power source such as a power grid or micro-turbine may need to be rectified to supply power to a DC load such as a tool, machine or appliance or the DC input of an inverter. A high voltage DC source may need to be stepped down to supply a low voltage load, or a low voltage DC source may need to be stepped up to supply a high voltage load. Other applications will become apparent to those skilled in the art based on the teachings herein.
Power modules are typically self-contained units that include a converter to transform and/or condition power from one or more power sources for supplying power to one or more loads. Power modules typically employ transistors, diodes and other components that generate substantial heat during operation, particularly when operating at high loads. Excessive heat can cause the components to under perform or even fail if not adequately addressed. Conventional power module structures employ various electrically insulating layers for electrically insulating the various components from one another and from the exterior of the power module. For example, components are typically mounted on direct bond copper (DBC) or direct bond aluminum (DBA) substrates, which comprise a ceramic substrate with metal foil fused on both sides. These electrically insulating layers also tend to be thermally insulating, significantly decreasing the ability to transfer heat away from the electronics.
Many applications for power converters are cost and/or size sensitive. These applications will employ other alternatives if sufficiently inexpensive converters are not available in packages with a sufficiently small footprint. Thus, it is desirable to reduce the cost and footprint of power converters, without reducing the rated power. It is further desirable to enhance the heat transfer characteristics in a power module, which may improve reliability and which may lower costs by reducing the amount of silicon required to accommodate the thermal characteristics of the power module. Further, it is desirable to be able produce a variety of power modules from relatively few common components, to cost effectively accommodate customers' varying requirements while incurring a minimal level in design costs and maintaining a minimal level of inventory.